Nelson and Marlborough residents are among those struggling to get on a waiting list for life-changing elective operations.

That is despite the Government's increased focus and funding of elective surgery, including $110 million of new funding announced in Thursday's Budget.

Health Minister Tony Ryall said the number of patients receiving elective surgery over the past five years had increased from 118,000 in 2008 to 158,000 in 2013.

But opposition politicians say the operations are not keeping pace with increasing demand, particularly as the population ages.

Others also accuse the Government of reducing numbers on the waiting list by raising the criteria to get onto it.

In Nelson and Marlborough, 6054 procedures were completed last year, and figures show a declining number on waiting lists.

The Government's national booking system - used primarily to measure how long patients are waiting for their appointments - has dropped from 3659 during the 2003-04 financial year to 2148 during 2011-12.

There are similar trends across the country, but surgeons, other health professionals and opposition politicians have questioned the seeming success.

Medical Association chairman Mark Peterson told Fairfax Media in March that patients who needed surgery were being told they did not qualify.

It is hard to accurately tell how many people are in the same predicament because there are no records kept.

The ministry takes note of how many people leave or are expelled from its booking system, but not why. Those who are taken off the list involuntarily are filed under the same category as patients who change their minds about surgery, switch to private providers or are judged medically unfit to proceed.

With that in mind, the raw figures are high. A total of 1573 or nearly a quarter of the Nelson and Marlborough patients entered into the national booking system were taken out of the system without surgery during 2011-12.

During the previous two years it was even higher at 29 per cent.

The national average has sat at 21 per cent or less between 2007-08 and 2011-12.

The Health Funds Association carried out a survey of 1830 people during September last year looking at this group.

An extrapolation from their results suggests there may be around 3570 people in Nelson and Marlborough who need elective surgery but have been excluded from the national booking system's waiting list.

Ryall has dismissed the survey. "The Health Funds Association survey is paid for by the private health insurers who are looking to drum up business."

He said the Government had made elective surgery a "real priority" by increasing funding in every budget.

"Demand for surgery will increase; the answer is to do more. That's why we have a national elective surgery target, and why record numbers of Kiwis are now receiving elective surgery."

Green Party health spokesman and former chief executive of the West Coast District Health Board Kevin Hague believed it was likely that a large number of people met the criteria for surgery and had been assessed as such, but had been ejected from the waiting list.

"What that allows the Government to do is say, ‘Well, there's been a reduced number of people who are waiting for surgery.' But it has no data at all about the remainder," Hague said. "This is part of the game with elective surgery: Make it look like the Government has done a lot because there's more money going in, more surgery, and apparently fewer people booked for surgery, but that's the missing part of the puzzle there."

He said pressure from himself and King had resulted in the creation of a new tool to measure these people.

From July 1, district health boards will be collecting information on referrals for the first specialist assessment. This information will help create a new list measuring "national patient flow".

A ministry spokesperson said they expected that it would take some time for the new data to produce complete and reliable information. Hague felt that the Government would find a way to "game" this initiative also.

He said the ministry's push on elective surgery was positive, but it did not go far enough to meet the increasing level of public need.

He was also concerned about declining case weights nationwide, which meant DHBs were favouring simple operations over more complicated, time-consuming procedures.

"When you factor in increasing population, increasing age of the population, increasing complexity of the disease or injury pattern as well as inflation - in order just to tread water against that pattern of increasing need, actually the system was about $100 million short-funded on what the increase needed to be in last year's Budget.

"And the year before it was about $100 million short-funded. And the year before that it was about $60 million short-funded."

Asked what he would do in Ryall's place, Hague said it was important to support the system to match the increase in need and pay more attention to primary and preventive healthcare.

"The fact [is] that this is a target and the minister's pressure around volumes is driving the system to meet the target rather than do the best job for patients. We've got to return it to that, to doing the best job, and the people with the biggest need should be prioritised first."

Ryall said Hague could "cast as many election-year aspersions about the national patient flow collection as he likes; the fact is more patients are getting treated sooner and that's what matters to the Government".

Labour health spokeswoman Annette King said she felt the lack of a list to measure unmet need was "absolutely disgraceful".

To fix the situation, she recommended an honest, transparent study be conducted to look into how many people were waiting to first access the waiting list and how many had missed their five-month deadline for an assessment or surgery.

"This whole six months, five months, now to be four months [timeline] is meaning people get bumped off."

King also advocated a review of unmet need nationally, and the establishment of a nationally consistent assessment tool.

THE ELECTIVE SURGERY PROCESS

1 The patient visits their primary care health provider, who is usually a GP.

2 The GP decides whether the patient will be referred to a specialist.

3 Once the referral is received, the specialist decides whether the patient's condition is serious enough for them to receive an assessment.

4 If the answer is "yes", then under the Ministry of Health's guidelines, the specialist needs to see that patient within five months. In December this year, that will change to four months. The patient is now on a waiting list.

5 If the answer is "no", the patient is referred back to their GP.

6 At the assessment, the specialist will look at their condition and recommend the best treatment based on their priority score. This score takes into account the patient's level of need and their ability to benefit compared to others.

7 If the patient qualifies for publicly funded elective surgery, then the Ministry of Health requires that the patient must receive treatment or a definite treatment date within five months of confirmation that surgery is needed. The patient is now on a second waiting list, and they lose their spot if their surgery cannot be completed within five months.

8 If the patient's priority score is close to the waiting list threshold but they don't make the cut, they will be re-assessed in five months' time.

9 If their score is well below the threshold, the patient will have to start all over again once their symptoms have worsened and their priority score has changed.